实习四 MyBatis
一、实习要求
1.掌握ORM概念及工作原理
2.掌握MyBatis的基本配置
3.掌握MyBatis的基本操作
4.了解MyBatis的高级查询
二、实习内容
创建一个表（books），包含字段：id（自动增长）、book_name（书名）、author（作者）、price（价格）、press（出版社）、press_date（出版日期）。
（1）基于映射文件（xml）完成对books的增删改查；
（2）基于接口及注解的增删改查
（3）使用动态SQL完成不确定项的查询，查询项包括除id之外的所有项，其中：书名、作者为模糊查询、价格、出版日期为范围查询。
三、实习过程
tip：所谓的id自动增长可以通过创建表定义列时设置，不过似乎不是所有数据库都支持，而本文是写了一个函数来获取最大id
工程结构：
主要代码：（所有代码可见工程目录）
Book.java
package entity;
public class Book {
private Integer id;
private String bookname;
private String author;
private Float price;
private String press;
private String pressdate;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getBookname() {
return bookname;
}
public void setBookname(String bookname) {
this.bookname = bookname;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public Float getPrice() {
return price;
}
public void setPrice(Float price) {
this.price = price;
}
public String getPress() {
return press;
}
public void setPress(String press) {
this.press = press;
}
public String getPressdate() {
return pressdate;
}
public void setPressdate(String pressdate) {
this.pressdate = pressdate;
}
@Override
public String toString() {
return "Book{" +
"id=" + id +
", bookname='" + bookname + '\'' +
", author='" + author + '\'' +
", price=" + price +
", press='" + press + '\'' +
", pressdate='" + pressdate + '\'' +
'}';
}
}
BookMapper.java
package mappers;
import entity.Book;
import org.apache.ibatis.annotations.*;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public interface BookMapper {
int getnewid();
//基于配置文件
List<HashMap<String,Object>> listAll();//查
Book getById(Integer id);//查
void add1( Map map);//增
void delbyid1(Integer id);//删除
void update1(Map map);//改
List<Book> dynamicfind(Map map);//动态sql
//基于注解
@Select("select * from books where author = #{author}")
Book getByAuthor(String author);//查
@Insert("insert into books values (#{id}, #{bookname},#{author},#{price},#{press},#{pressdate})")
void add2(@Param("id") int id , @Param("bookname") String bookname, @Param("author") String author,
@Param("price") Float price, @Param("press") String press, @Param("pressdate") String pressdate);//增
@Update("update books set book_name=#{bookname}, author=#{author}, price=#{price}, press=#{press}, press_date=#{pressdate}\n" +
" where id=#{id}")
void update2(@Param("id") int id , @Param("bookname") String bookname, @Param("author") String author,
@Param("price") Float price, @Param("press") String press, @Param("pressdate") String pressdate);//改
@Delete("delete from books where id=#{id}")
void delbyid2(int id);//删
}
Main.java
import entity.Book;
import mappers.BookMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Main {
public static void main(String argc[]) throws IOException {
InputStream is = Resources.getResourceAsStream("Mybatis-config.xml");
SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(is);
SqlSession session = ssf.openSession();
BookMapper mapper = session.getMapper(BookMapper.class);
//基于配置文件
//查
List<HashMap<String,Object>> rs = mapper.listAll();
System.out.println(rs.toString());
Book r = mapper.getById(3);
System.out.println(r.toString());
//增
Map map=new HashMap();
map.put("id", mapper.getnewid()+1);
map.put("bookname","大学英语");
map.put("author","bb");
map.put("price",Float.valueOf("18"));
map.put("press","a出版社");
map.put("pressdate","1999/2/2");
//mapper.add1(map);
//删
//mapper.delbyid1(6);
//改
Map map1=new HashMap();
map1.put("id", 7);
map1.put("bookname","大学物理");
map1.put("author","bb");
map1.put("price",Float.valueOf("18"));
map1.put("press","a出版社");
map1.put("pressdate","1999/2/2");
//mapper.update1(map1);
//基于注解
//查
Book rr = mapper.getByAuthor("tom");
System.out.println(rr.toString());
//增
//mapper.add2(10,"移动软件开发","李彬",Float.valueOf("29.5"),"西农出版社","2021/12/1");
//改
mapper.update2(10,"移动软件开发","李彬",Float.valueOf("139.5"),"西农出版社","2021/12/1");
//删
//mapper.delbyid2(10);
//动态sql
Map map2=new HashMap();
//map2.put("bookname","大学");
//map2.put("author","李");
map2.put("price",Float.valueOf("10"));
//map2.put("press","");
List<Book> list1=mapper.dynamicfind(map2);
for(Book book:list1)
{
System.out.println(book);
}
session.close();
}
}
BookMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="mappers.BookMapper">
<select id="getnewid" resultType="int">
select max(id) from books
</select>
<select id="listAll" resultType="hashmap">
select * from books
</select>
<select id="getById" parameterType="int" resultType="Book">
select * from books where id= #{id}
</select>
<select id="dynamicfind" parameterType="map" resultType="Book">
select * from books where 1=1
<if test="bookname!=null and bookname!=''">and book_name like concat('%',#{bookname},'%')</if>
<if test="author!=null and author!=''">and author like concat('%',#{author},'%')</if>
<if test="price!=null and price!=''">and price between #{price}-10 and #{price}+10</if>
<if test="press!=null and press!=''">and press like concat('%',#{press},'%') </if>
</select>
<insert id="add1" parameterType="map">
insert into books values( #{id}, #{bookname}, #{author}, #{price}, #{press}, #{pressdate} )
</insert>
<delete id="delbyid1" parameterType="int">
delete from books where id = #{id}
</delete>
<update id="update1" parameterType="map">
update books set book_name=#{bookname}, author=#{author}, price=#{price}, press=#{press}, press_date=#{pressdate}
where id=#{id}
</update>
</mapper>
实验结果：
例如动态sql的结果：
查找书名包含“大学”并且价格在0到20：
结果：
其他的不放了